Impact-tool.



No. vel-,414. PATENTED MAY s1', 1904.

w. SECHER 6; L. wGRm/"rl y IMPAGTTUOL;

APPLIGATION FILED NOV.30, 1903.

N0 MODEL.

' able clip 1.

No. 761,414.i

UNITED l STATES Patented May 31, 1904.

PATENT OFFICE.

WILLIAM sEcII'EE AND LOUIs w. GREVE, OE CLEVELAND, OHIO.

SPECIFICATION forming part of Letters Patent Ive.` 761,414, dated May s1, l1904..

" Appiieeaen ined November 3o, 1903. serial Ne. 183,089. (No model.) n

formiembodying the invention, such detail construction being but one of various mechanical fo rms in which the principle of the invention may be used.

In said annexed drawings, Figure I represents an axial section of our improved pneumatic impact-tool,.sl1owing the plunger in the position in which ithas shifted the Valve to admit air behind the plunger'- to drive the same forward or outward; and lFig. II, a similar section with the plunger in its forward position and the valve shifted tol admit air in front of the plunger to drive the same back.

The tool has a barrel 1, the bore of which forms the working cylinder. The outer or forward end of this cylinder is formed with a "tool-socket 2, in which the shank of the working tool 3 fits and isvheld by means .of a snit- The tool may be a chisel, calking-tool,'rivet set, or. whatever shape of workingtool is required for the work to be done by such working tooluhderimpact. A plunger 5 is fitted to reciprocate within the working cylinder. t The inner end of the cylinder has an external flange'andbears against the forward face of a .disk 7 t, having a'central aperture surrounded vby a flange 8, which fits 'into the inner end of the working cylinder.

The rear face of this ldisk bears against the forward face of a cylindrical valve-block 9, against the rear end of which a button 10 bears. This button fits in acrecess inthe bottom of a socket 11, formed upon a closed handle 12. The outside of this handle-socket is screw-threaded, and a longitudinally-split coupling-sleeve 13 has an internal screw- :air-hose may be attached, and an inlet-channel 17 extends from said socket and through the handle to the bottom of the handle-socket, where it forms an annular inlet-recess 18, which is open into thebutton-recess in the bottom of the handle-socket. The valve-block has an t axial valve-chamber 19 in its forward portion,

which valve-chamber is of slightly greater diameter than the centralfianged opening in the disk.

with a chamber 20.of less diameter and extending through the rear end ofthe valve-block.

Thel button which closes the rear end ofthe valve-block has a recess 21 in its forward face,

` which recess registers with the rear endnof the ssmall-diametervalve-chamber. Alive-air injlet 22 extends through the button and the wall of the valve-block to near the forward end of the same, and a groove 23 inthe face of the button connects the recess in the latter to the live-air inlet. The forward end of the live- This forward chamber communicatesl air inlet-channel'22 communicates with an annular live-air port 24: in the large-diameter valve-chamber immediately to the rear of the Banged disk. An annular distributing-port 25 is formed in this valve-chamber to the rear of the inlet-port and communicates through a channel 26 with the forward end of the- IOO annular cylinder-exhaust port 31 is formed at the rear of the exhaust-port 27 and in the small-diameter valve-chamber, and said port communicates by a channel 32 through the valve-block and cylinder-wall with an exhaust-port 33 into the working cylinder a distance from the rear or inner end of the latter. An exhaust-port 34 is formed near the outer or forward end of the working cylinder through the wall of the same and leading to the atmosphere and serves as an auxiliary exhaust from that end of the working cylinder for the air in front of the forwardly or outwardly moving plunger. An escape-port 35 is formed through the wall of the working cylinder a distance from the forward end of the same and the inner end of the tool-shank slightly in excess of the length of the plunger, so that said port will be uncovered by the plunger when the latter arrives at the forward extreme of its throw to permit the air behind the `plunger 'to escape and the pressure l behind the plunger to be reduced. A cylindrical valve reciprocate's in the two-diameter valve-chamber and has a long small-diameter piston 36, which fits in the small-diameter chamber, a recess 37 forward of this latter piston, and a short small-diameter piston 38 forward of this recess. A large-diameter piston 39 is formed immediately forward of the short small-diameter piston to close the forward end of the small-diameter chamber when the valve is in its rearward position and to cut off forward communication to the exhaustport when the valve is in its forward position. The valve has a reduced neck 40 forward of this piston and has a piston 41, which has play at both sides of the live-air inlet-port in the forward end of the valve-chamber. A throttle-valve 42 controls admission of air through the live-air inlet-channel and is operated by a suitable trigger 43.

When live air is admitted into the tool, the channel leading from the inlet-channel to the rear end of the valve-chamber will place live air permanently against the small-diameter rear face of the valve, thus having a permanent tendency to force the valve forward. When the parts are in the positions illustrated in Fig. I, the valve has been forced rearward by the action of the returning plunger upon the air trapped between the rear-end exhaust 33 and the forward large-diameter face of the valve, compressing such air, and the valve is held in this position by the pressure of the live air, which is admitted through the uncovered inlet-port into the inner end of the working cylinder and back of the plunger, acting against the large area of the forward endv of the valve and overcoming the same pressure against the small-area rear face of the valve. Of course the compressing action of the returning plunger against the largediameter face of the valve and upon the air trapped will overcome and begreater than the forward pressure of the normal live air against the sm all rear area of the val ve and will push the valve rearward against this pressure, whereupon the valve will be held in its rear position by the differential action of the live air against the differential faces or areas of the valve. The air entering the inner end of the working cylinder drives the plunger forward, and the advancing plunger drives the air in front of the same out through the auxiliary exhaust and through the distributingpassage 26, whence it exhausts through the. distributing-port 25 and the exhaust-port in the valve-chamber. Then the plunger arrives at the forward extreme of its throw and strikes the shank of the working tool, eil'ecting its operative blow upon said tool, the plunger uncovers the escape-port in the working cylinder and the live air behind thev plunger is thus relieved and the pressure of the same is reduced, so that the constant liveair pressure acting against the small-area face of the valve can force the valve forward against the reduced pressure upon the forward large-area face of the valve, and thus shift the same to accomplish the rearward or inward throw ofthe plunger. The recess in the valve around the neck of the same connects the forward distributing-channel with the live-air inlet and admits live air forward of the plunger to force the same rearward. rllhe air behind the returning plunger escapes through the rear exhaust-port and channel through the recess in the rear part of the valve and out through the exhaust-port and passages. When the returning plunger has passed the rear exhaust-port, it cuts oli' cxhaust from the rear end of the working cylinder and compresses the air trapped therein until the pressure thus produced overcomes the forward pressure permanently against the rear small-area face of the valve by its aetion against the large-area forward face of the valve and shifts the valve rearward, when the entire operation of the parts is again repeated.

The valve in this tool is thus actuated by constant pressure against one face and intermittent increased pressure of air compressed by the returning plunger. By thisactuation of the valve great simplicity of construction and operation of the tool is attained, and the valve is shifted with great rapidity, causing great speed and strength of the blow of the plunger upon the shank of the working tool.

Other modes of applying the principle of our invention may be employed for the mode herein explained. Change may therefore be made as regards the mechanism thus disclosed, provided the principles of construction set forth, respectively, in the following claims are employed.

lOO

IIO

' distinctly claim as our inventiondifferential-pressure areas and having its l. .In an impact-tool of the type described, a valve to control the admission and exhaust to and from the cylinder, said valve being constructed and arranged with a permanent live-air admission against one face'to force it in one direction and with an opposed'i'ace exposed to air compressed between it and the plunger to force it in the opposite direction.

2. In an impact-tool of the type described, a valve to control the admission and exhaust to and `from the `cylinder, said valve having smaller pressure'area exposed to constant live-air pressure to move 1t 1n one direction at one' stroke of the plunger and being moved in the opposite direction by compression of the air between its large pressure area and the plunger at the .return stroke. A

3. In an impact-tool of the type described, a valve to control the admission and exhaust to and 'from the cylinder, said Valve having one pressure area permanently exposed to the liveair pressure and` having an opposed pressure area exposed to airpompressed between it and the returning plunger.

4. In an impact-tool, the combination of a cylinder, a plunger reciprocable thereiminlet and exhaust passages for the motive iuid, and a valve movable in a chamber at one end of the cylinder; and serving to control the flow of fluid to and from each end of the cylinder, one face of said valve being permanently exposed to motive-lluid pressure and the other face being exposed to the -action'of motive fluid compressed by the returning plunger.

5. In an impact-tool, the combination of a cylinder, a plunger reciprocable therein, inlet and exhaust passages for the motive fluid, and a valve serving to control the flow of motive fluid to and from each end of the cylinder, said valve having yone face exposed to the action of motive Huid 4compressed by the returning plunger and another face permanently exposed to the motive Huid under normal pressure.

`6. In an impact-tool, the combination of a a valve controlling the flow of-motive Huid to and from each end of the cylinder, said valve having one face exposed to the action of mocylinder, a plunger'reciprocable therein, and

tive fluid compressed by the plunger as the .latter approaches oneend of itsv stroke and another face of smaller area and exposed to ernanent normal pressure of the motive A 7. In animpact-tool, the combination of a cylinder, a plunger reciprocable therein, a valve-chamber, and a dilerential piston-valve in said chamber controlling the inlet and exhaust of motive fluid to and from the opposite ends ofthe cylinder, said valve having a pressure-face exposedl to air compressed by the plunger at one end of its stroke to be moved` in one direction and having another pressureface permanently exposed to motive-Huid pressure to be moved in the opposite direction.

.In testimony that we claim the foregoing to be our invention we have hereunto set our hands this 19th day of November, A. D. 1908.

wM. snoHEn. g '.LOUIS W. GREVE. Witnesses:

C. E. JOHNSON, Jr., 1 H. SUssnR.` 

